Method and apparatus for treating crimped yarn



Dec. 24, 1968 A. L. TRIFUNOVIC ETAL 3,417,447

METHOD AND APPARATUS FOR TREATING CRIMPED YARN Filed 001.. 21, 1965 2 Sheets-Sheet 1 A gNvzmoRs LEXAN an aura/mun 8 IV. EZGIS Dec. 2 4, 1968 A. L. TRIFUNOVIC ETAL 4 METHOD AND APPARATUS FOR TREATING CRIMPED YARN Filed on. 21, 1965 2 Sheets-Sheet 2 J mm mwz n H TF. N v//// mm m Rm Mm p1 m m i a United States Patent 3,417,447 METHOD AND APPARATUS FOR TREATING CRIMPED YARN Alexander L. Trifunovic and Steve E. Zeis, Wilmington,

Del., assignors to Joseph Bancroft & Sons Co., Wilmington, DeL, a corporation of Delaware Filed Oct. 21, 1965, Ser. No. 499,662 3 Claims. (Cl. 2871.3)

ABSTRACT OF THE DISCLOSURE Apparatus for treating crimped yarn derived from a core of a stuifer crimper including a heated stepped roll and a parallel guide roll around which the yarn is looped for heating and stretching and a winder receiving the yarn from said rolls. A motor for driving the rolls is controlled by a potentiometer actuated by a sensing element responsive to the level of the core of yarn and connected to maintain the level substantially constant. The crimped yarn is stretched at a temperature below the original setting temperature and is rebulked by relaxation at a temperature higher than the stretching temperature.

This invention relates to apparatus for packaging crimped yarn and more particularly to the packaging of yarn as derived from a stutter crimper.

An object is to provide an apparatus of the above type which is adapted and arranged for the treatment of the yarn at a stage after stuifer crimping and prior to windmg.

Another object is to provide means for processing a stutter crimped and heat set yarn for improving its rebulking characteristics.

Another object is to provide a processing stage adapted to minimize the tendency of a yarn of the above typ to rebulk at room temperatures during subsequent processing operations.

Another object is to provide novel and improved means, in apparatus of the above type, for maintaining uniform conditions of back pressure and yarn tension during the crimping and winding operations.

Another object is to provide a sensitive and continuous control of the core of crimped yarn in the crimping chamber.

Another object of this invention is to provide a new and improved means of imparting a temporary straight set to any stuffer crimped yarn that has a tendency to relax and redevelop its crimp at room temperature prior to being placed in a fabric.

Another object is to provide new and improved means of dephasing the individually crimped filaments in stuffer crimped multi-fil-ament yarns relative to each other.

Another object is to increase the angle or pitch of the crimp in the filaments of such yarn.

Another object is to provide new and improved means for accomplishing the above objects in a continuous operation and also to combine this operation with the stuffer crimping operation in a rcontinuus process.

It has been found that thermoplastic yarns such as nylon which have been crimped in a stuffer crimper, heat set and wound onto a package under a straightening tension become temporarily straight set and, under proper conditions, may be woven or otherwise processed in straight form and subsequently rebulked after processing. However, under some conditions such yarns have a tendency to rebulk to a limited extent at room temperature prior to or during subsequent processing. This is particularly troublesome with the higher denier yarns, such as multifilament carpet size yarns. Such rebulking interferes with the standard processing techniques and makes the control of tension difiicult.

3,417,447 Patented Dec. 24, 1968 The present invention overcomes this problem by imparting to the yarn, prior to Winding, a further temporary straight set which reduces the tendency of the yarn to rebulk at room temperature but does not interfere with the rebulking of the yarn in the fabric, when relaxed by sub sequent steam treatment.

In one embodiment this is accomplished by subjecting the crimped and heat set yarn as derived from the stutter crimper to a temperature below the setting temperature to which the yarn was subjected in the stuifer crimper but sufficiently high to prevent subsequent relaxing at room temperature and simultaneously subjecting the yarn to a limited stretching tension.

When such a yarn is finally rebulked in the fabric it is found that the angle of crimp is somewhat greater than in the case of yarns hav not been so processed and that the final bulk is greater than in yarns having initially the same angle of crimp.

The nature of the invention will be better understood from the following description, taken in connection with the acompanying drawings in which a specific embodiment has been set forth for purposes of illustration.

In the drawings:

FIG. 1 is an elevation of an apparatus embodying the invention;

FIG. 2 is an axial section through the stretching and heating rolls on a larger scale; and

FIG. 3 is a detail of a modified form of stretch roll.

Referring to the drawings more in detail, the invention is shown as embodied in an apparatus for the treatment of a yarn 10 which is extracted from the core 11 of crimped and heat set yarn in the cooling cage 12 of a stuifer crimper 13 of the type shown more in detail in the copending application Ser. No. 406,240 filed Oct. 26, 1964, and which comprises a crimping chamber of generally rectangular cross-section into which the yarn is fed by a pair of feed rolls to be folded over and crimped against a mass of previously crimped yarn held compacted in the chamber and passed as a core through a heating zone wherein the yarn is heated to a temperature adapted to effect a permanent set of the crimp. The core of crimped yarn is then advanced through the cooling cage 12 between a set of spaced confining rods 14 which are secured to the end of the crimping chamber 13. The yarn 10 may be of the multifil-ament type of carpet size wherein the crimps are set into each filament.

In accordance with the present invention a bar 21 mounted in a frame 22 extends across and rests on the top of the core 11 in the cooling zone 12 of the crimper and provides a controlled back pressure on the core 11. The yarn 10 is withdrawn from under this bar 21 through a tension gate 25 and eye 24a to a heating and stretching stage comprising a heated, stepped roll 31 having a portion 32 of smaller diameter and a portion 33 of larger diameter. The roll 31 is mounted on a shaft 34 which is driven by a motor 35 through a belt 36. The portion 33 of the stepped roll 31 is shown as hollow and is provided with heating means in the form of a plurality of heating elements 38 mounted on a fixed sleeve 40 disposed around the shaft 34 and supported by a bracket 39.

A temperature sensing device 41 also carried by bracket 39 is disposed to sense the temperature of the surface of the roll 31 and is connected to control the heating elements 38 so as to maintain the surface of the roll at a constant, predetermined temperature.

A spacer roll 43 having separate portions 44 and 45 which are journalled on bearings on a rod 46 is spaced from the stepped roll 31 for carrying yarn loops 51 and 52. The roll 43 is generally parallel to the roll 31 but is inclined slightly away from the roll 31 in the direction of feed of the yarn loops.

The yarn 10, after passing through the tension gate 25, is passed around the rolls 31 and 43 in the form of loops 51 and 52 and then passes through an eye 53 to a winding 54 which rests on and is driven by a drive roll 55 which is driven from the shaft 34 by a belt 56. The rate of drive of the winding is adjusted with respect to the rate of the roll 31 so as to maintain the yarn under constant tension as it is fed to the winding.

As the yarn loops 51 pass along the surface of the portion 32 of the roll 31 the yarn becomes heated to a temperature suficiently high to produce a temporary straight set and to facilitate the stretching of the yarn as the loops reach the stepped portion of the roll but below the temperature at which the permanent set, which is effected in the crimping chamber, would be affected. This post heating and stretching minimizes the rebulking of the yarn at room temperatures prior to the completion of the subsequent processing operation.

In order to control the rate of the motor so as to maintain a constant back pressure on the core 12 in the crimping chamber, the motor 35 is connected to be regulated by a potentiometer 61 having a shaft 62 carrying a sprocket 63 which is driven by a chain 64 from a sprocket 65. The sprocket 65 carries a pin 66 which is actuated by a forked arm 67 which is pivoted at 68 and has a forked end 69 actuated by a pin 70 carried by the frame 22. The arrangement is such that the raising or lowering of the bar 21 causes a movement of the sprocket 65 which is transferred to the potentiometer shaft to vary the speed of the motor 35 and a corresponding change in the rate of the stepped roll 31 and of the winder 55 in a sense adapted to maintain'the bar 21 at a substantially constant level. In this way a constant back pressure is maintained on the core which is esesntial in producing a uniform crimp, and due to the common drive of the roll 31 and of the winder, the yarn is wound on the package 54 under a constant tension. When the yarn is subsequently rebulked, a uniform bulk and crimp angle is assured.

In the embodiment of FIG. 3 the stepped roll 31 is shown as heated by a plurality of heating elements 72 which are mounted on the fixed sleeve 73 and a temperature sensing device 75 is carried by the sleeve in a position to sense the temperature at the inner surface of the walls of the stepped roll 31.

The initial tension applied to the yarn between the gate tension and the first wrap on the stepped roller, the number of wraps on both sections of the stepped roller, the diameter and ratio of the surfaces of the stepped roller, the surface heat of the stepped roller, and the speed at which the stepped roller rotates, are all important factors in carrying out the invention and may vary depending on the results desired.

In a specific example, a single end of 2080 total denier semibright nylon yarn with 136 filaments and a one-half turn twist in the 8 direction was initially crimped in a stuifer crimper at approximately the 40 percent bulk level, where bulk represents the amount of shrink-age of a yarn after being fully relaxed in boiling water. The yarn was wrapped five times around the circumference of each surface of the stepped roller. The larger surface circumference measured approximately 17" and smaller surface circumference measured 13". The surface speed of the larger circumferential surface Was approximately 200 y.p.m. and the surface temperature of the stepped roller was approximately 250 F. The initial tension between the gate tension and the first wrap on the stepped roller was approximately 200 grams. The resultant yarn was tested and found to be at approximately the 35 percent bulk level.

A comparison of this yarn with a similar yarn crimped in the same stutter crimper but at approximately the 35 percent bulk level and without further processing under this invention, after both yarns had been relaxed in boiling water, revealed that the crimps in the filaments 0f the yarn of this invention had larger angles; the crimped filaments were more completely dephased; and the yarn was loftier, more resilient and had better recovery power. In addition, before either yarn was conventionally relaxed by boiling off procedures, the yarn of this invention had a much slower rate of recovery at room temperature than the other yarn Where both were free to relax under no tension. This was, of course, a temporary condition which only existed until the yarn was relaxed by boiling oft procedures.

While the invention has been described with a heated stepped roller, it is also possible to employ other known means capable of imparting the required tension and heat to the yarn. Further, in connection with the stepped roller, more than two steps can be used when it becomes necessary to stretch the yarn in more than one stage.

A thick and thin or variably bulked yarn may be produced by the stretching step above described from a continuous filament synthetic yarn which has been variably drawn prior to crimping so as to contain highly drawn and less highly drawn portions. Such a yarn may be crimped and heat set in a stuffer crimper as described above or by any of the other popular crimping processes to impart a substantially uniform crimp thereto. The crimped yarn is then stretched on the poststretching unit described above. The stepped roll 31 and the spacer roll 43 should be spaced so that sections of the drawn and undrawn portions of the yarn are always subjected to stretching at the same time.

It has been found that when such a yarn has been stretched the portions of the yarn that were less highly drawn prior to crimping become drawn out and all or a substantial part of the crimp imparted during the crimping operation is permanently removed while the portions that were more highly drawn prior to crimping still retain the crimp upon subsequent relaxation. The stepped roll 31 may be heated or not, depending upon whether or not heat is required in stretching of the less highly drawn portions.

What is claimed is:

1. The method of producing a bulked yarn which comprises crimping a heat settable multifilament thermoplastic yarn under conditions to impart a crimp which is substantially in phase in the various filaments and heating the yarn to a temperature to produce a permanent set to the crimp, extracting the crimped yarn under a straightening tension and stretching the yarn at a temperature below the temperature at which the crimp was set in the yarn but above room temperature to impart a temporary straight set to the yarn, and, subsequently, heating the yarn to a temperature to remove the temporary straight set and to cause the crimps to reform with the crimps in the various filaments dephased to thereby produce a yarn having improved bulk characteristics.

2. In combination, a yarn crimping apparatus having a crimping chamber and means forming a core of crimped yarn, and means extracting the crimped yarn under tension from the output end of said core, said last means comprising a stepped roll having areas of smaller and larger diameters, respectively, means including an idler roll for passing said yarn around said stepped roll in a series of loops, beginning with said smaller diameter area and ending with said larger diameter area whereby the yarn is stretched as it passes on to said larger diameter area, means heating said stepped roll to a yarn drawing temperature, yarn winding mechanism, and means feeding the stretched yarn from said stretching mechanism to said winding mechanism.

3. Apparatus as set forth in claim 2 including temperature sensing means connected to control said heating means to maintain the surface of said stepped roll at a predetermined temperature.

(References on following page) UNITED 5 6 References Cited 3,200,466 8/ 1965 Duga et a1 281 Shattuck et a1. ir 1 28 71 3 X LOUIS K. RIMRODT, Rrimary Examiner.

ee am m et a Johnson 5 us. 01. X.R.

Scott 28-72 72 

